Vinyl chloride

75-01-4

Hazard Summary-Created in April 1992; Revised in January 2000

Most vinyl chloride is used to make polyvinyl chloride (PVC) plastic and
vinyl products. Acute (short-term) exposure to high levels of vinyl
chloride in air has resulted in central nervous system effects (CNS),
such as dizziness, drowsiness, and headaches in humans. Chronic
(long-term) exposure to vinyl chloride through inhalation and oral exposure
in humans has resulted in liver damage. Cancer is a major concern
from exposure to vinyl chloride via inhalation, as vinyl chloride exposure
has been shown to increase the risk of a rare form of liver cancer in
humans. EPA has classified vinyl chloride as a Group A, human carcinogen.

Uses

Most of the vinyl chloride produced in the United States is used
to make polyvinyl chloride (PVC), a material used to manufacture a variety
of plastic and vinyl products including pipes, wire and cable coatings,
and packaging materials. (1)

Smaller amounts of vinyl chloride are used in furniture and automobile
upholstery, wall coverings, housewares, and automotive parts. (1)

Sources and Potential Exposure

Ambient air concentrations of vinyl chloride are generally quite
low, with exposure occurring from the discharge of exhaust gases from
factories that manufacture or process vinyl chloride, or evaporation
from areas where chemical wastes are stored. (1,2)

Air inside new cars may contain vinyl chloride at higher levels than
detected in ambient air because vinyl chloride may outgas into the air
from the new plastic parts. (1,2)

Drinking water may contain vinyl chloride released from contact with
polyvinyl pipes. (1,2)

Vinyl chloride is a microbial degradation product of trichloroethylene
in groundwater, and thus can be found in groundwater affected by trichloroethylene
contamination. (3)

Occupational exposure to vinyl chloride may occur in those workers
concerned with the production, use, transport, storage, and disposal
of the chemical. (1,2)

Assessing Personal Exposure

Vinyl chloride can be detected in urine and body tissues, but the
tests are not reliable indicators of total exposure. (1,2)

Health Hazard Information

Acute Effects:

Acute exposure of humans to high levels of vinyl chloride via inhalation
in humans has resulted in effects on the CNS, such as dizziness, drowsiness,
headaches, and giddiness. (1,2)

Vinyl chloride is reported to be slightly irritating to the eyes
and respiratory tract in humans. (1,2)

Acute exposure to extremely high levels of vinyl chloride has caused
loss of consciousness, lung and kidney irritation, and inhibition of
blood clotting in humans and cardiac arrhythmias in animals. (1)

Tests involving acute exposure of mice have shown vinyl chloride
to have high acute toxicity from inhalation
exposure. (5)

Chronic Effects(Noncancer):

Liver damage may result in humans from chronic exposure to vinyl
chloride, through both inhalation and oral exposure. (1,2)

A small percentage of individuals occupationally exposed to high
levels of vinyl chloride in air have developed a set of symptoms termed
"vinyl chloride disease," which is characterized by Raynaud's phenomenon
(fingers blanch and numbness and discomfort are experienced upon exposure
to the cold), changes in the bones at the end of the fingers, joint
and muscle pain, and scleroderma-like skin changes (thickening of the
skin, decreased elasticity, and slight edema). (1,2)

Animal studies have reported effects on the liver, kidney, and CNS
from chronic exposure to vinyl chloride. (1,6)

EPA has established a Reference Concentration (RfC)
of 0.1 milligrams per cubic meter, and a Reference Dose (RfD)
of 0.003 milligrams per kilogram per day for vinyl chloride. Please
see IRIS for current information. (8)

Reproductive/Developmental Effects:

Several case reports suggest that male sexual performance may be
affected by vinyl chloride. However, these studies are limited by lack
of quantitative exposure information and possible co-occurring exposure
to other chemicals. (1)

Several epidemiological studies have reported an association between
vinyl chloride exposure in pregnant women and an increased incidence
of birth defects, while other studies have not reported similar findings.
(1,2)

Epidemiological studies have suggested an association between men
occupationally exposed to vinyl chloride and miscarriages in their wives'
pregnancies although other studies have not supported these findings.
(1,2)

Testicular damage and decreased male fertility have been reported
in rats exposed to low levels for up to 12 months. (1)

Animal studies have reported decreased fetal weight and birth defects
at levels that are also toxic to maternal animals in the offspring of
rats exposed to vinyl chloride through inhalation. (1)

Cancer Risk:

Inhaled vinyl chloride has been shown to increase the risk of a rare
form of liver cancer (angiosarcoma of the liver) in humans. (1,2,6)

Animal studies have shown that vinyl chloride, via inhalation, increases
the incidence of angiosarcoma of the liver and cancer of the liver.
(1,2,6)

Several rat studies show a pronounced early-life susceptibility to
the carcinogenic effect of vinyl chloride, i.e., early exposures are
associated with higher liver cancer incidence than similar or much longer
exposures that occur after maturity. (1)

EPA uses mathematical models, based on animal studies, to estimate
the probability of a person developing cancer from breathing air containing
a specified concentration of a chemical. EPA has calculated an
inhalation unit risk estimate of 8.8 × 10-6 (µg/m3)-1
for lifetime exposure to vinyl chloride. Please see IRIS for current
information. (8)

EPA has calculated an oral cancer slope factor of 1.5 (mg/kg/d)-1
for lifetime exposure to vinyl chloride. Please see IRIS for current
information. (8)

Health Data from Inhalation Exposure

ACGIH TLV--American Conference of Governmental and Industrial Hygienists'
threshold limit value expressed as a time-weighted average; the concentration
of a substance to which most workers can be exposed without adverse effects.
LC50 (Lethal Concentration50)--A calculated
concentration of a chemical in air to which exposure for a specific length
of time is expected to cause death in 50% of a defined experimental animal
population. OSHA PEL--Occupational Safety and Health Administration's permissible
exposure limit expressed as a time-weighted average: the concentration of
a substance to which most workers can be exposed without adverse effect
averaged over a normal 8-h workday or a 40-h workweek. OSHA PEL ceiling value--OSHA's permissible exposure limit ceiling
value; the concentration of a substance that should not be exceeded at any
time.

The health and regulatory values cited in this factsheet were obtained
in December 1999. aHealth numbers are toxicological numbers from
animal testing or risk assessment values developed by EPA. bRegulatory numbers are values that have been
incorporated in Government regulations, while advisory numbers are nonregulatory
values provided by the Government or other groups as advice. OSHA
numbers are regulatory, whereas ACGIH numbers are advisory. cThe LOAEL is from the critical study used
as the basis for the ATSDR intermediate-duration inhalation MRL. dThe LOAEL is from the critical study used
as the basis for the CalEPA chronic inhalation reference exposure level.

J.E. Amoore and E. Hautala. Odor as an aid to
chemical safety: Odor thresholds compared with threshold limit values
and volatilities for 214 industrial chemicals in air and water dilution.
Journal of Applied Toxicology, 3(6):272-290. 1983.